Years and years ago. I see you've tried many things but not described whatever issues you may have had with them. I use Nextcloud running on a NAS which also runs a Wireguard endpoint so I have access via VPN to my home network when I am traveling. It's not perfect but does what I want it to do syncing a folder of files between Linux, Windows, and macOS systems, and the iOS app works well enough.

I don't use it for large scale file storage, such as photos or media. Those are on the NAS and accessed through traditional SMB file shares.